This invention relates to a water soluble solid ophthalmic insert for the treatment of dry eye syndrome, comprising a water soluble solid polymer insert of appropriate size to readily fit into the cul-de-sac of the eye. It also relates to a method of treating dry eye syndrome patients by applying the solid unmedicated ophthalmic insert into the cul-de-sac; to compositions of said insert, and to a process for preparing these inserts.
The treatment of dry eye syndrome has, in the past, been carried out by the use of ophthalmic preparations which served as wetting agents in the eye to keep the eye moist. These preparations have been of two general types: (1) aqueous solutions or suspensions or (2) ointments.
Historically, these ophthalmic preparations were isotonic aqueous solutions, buffered to the required pH, sterile and contained additives for improved viscosity and longer retention in the eye. However with these solutions, there are problems of dosage, irritation to the eye, stability and most importantly brief duration of effect. In fact, these aqueous solutions are effective for, at the most, a few minutes or so. It was partly because of this very short retention time that ophthalmic solutions were employed using water soluble polymer such as methylcellulose and other related cellulose derivatives as well as polyethylene oxide among others (see for example, U.S. Pat. Nos. 3,767,788, 3,767,789, emp, M.A. Int. Ophthal. Clin. 13 (No. 4) page 145 (1973) and 13 (No. 1) page 221 (1973), "External Eye Problems in the Elderly" by Frederick H. Theodore, M.D. Gereatrics 30: 71-77, April 1975 and Annals. of Ophthalmology by Bach et al, Vol. 4, pages 116-119 (1972) in an attempt to prolong the effectiveness of the preparation in the eye. The use of these polymers added to the viscosity of these ophthalmic solutions thereby affording a longer contact time of the medication with the eye. Nonetheless, these higher viscosity ophthalmic preparations are effective for no more than five to ten minutes and accordingly still require frequent applications to the eye to be effective. A recent application, Ser. No. 553,399 filed Feb. 26, 1975 discloses the use of hydroxypropylcellulose in solid form as a carrier for a medicament, such as pilocarpine, in the treatment of glaucoma. Here the hydroxypropylcellulose is employed as a carrier for the medicament but as in other applications to also afford further contact time of the medication with the eye. However, there is no suggestion therein that the insert does dissolve at a uniform rate or for that matter that it would be effective in the treatment of dry eye, but rather the medicament is leached out of the hydroxypropylcellulose which eventually dissolves.
It is an object of the present invention to provide an ophthalmic insert which serves as an artificial tear material useful for the treatment of dry eye characterized by having a long effective action over a period of at least several hours. This ophthalmic insert, therefore, when inserted in the cul-de-sac of the eye slowly dissolves, affording a continuous long term release of artificial tears and thereby eliminating the need for frequent installation of eye drops or ointments.
It has been surprisingly found that a non-toxic water soluble solid polymer inserted into the cul-de-sac of the eye is effective in relieving the symptoms of dry eye. It was not expected that such a polymer, which in the past had been used merely as a viscosity agent, could in a solid form act by itself to relieve such symptoms. It has also been surprising to find that such a water soluble polymer in solid form could uniformly dissolve in the eye and provide "artificial tear" for a period of at least several hours. This is particularly true of patients with dry eye syndrome since with limited amount of water available in the eye of such a patient, it would not be expected that proper dissolution of the polymer would occur.